1. Field of the Invention
This invention relates to an accessory for a D-rung ladder and, more particularly, to a paint tray holder for such ladders.
2. Description of the Prior Art
Many devices have been proposed from time-to-time to assist craftsmen overcome any awkwardness when working on a ladder. During the past decades, ladders have seen changes from wooden extension ladders to those of extruded aluminum and other composite materials. The extruded aluminum ladders initially replicated the wooden ladders and had round rungs that were swaged or otherwise attached to the extruded side rails.
The early accessories were designed to be accommodated by the ladder construction and, as cylindrical, hollow rungs came into use, several devices were adapted to function cooperatively with one or more rungs. These devices had varying degrees of adaptability and adjustability and are described hereinbelow in the review of the patent art known to the inventor. These devices are generally difficult to manufacture, expensive to acquire, and awkward to mount.
As ladder manufacturing technology evolved standards for safety were developed and relevant American National Standards Institute (ANSI) standards developed. One ANSI standard indicates, for example, that the optimal angle for setting up a ladder is 75xc2x0 (approx.). Other safety and manufacturing restraints have been promulgated.
In the 1980""s and 1990""s, the use of D-shaped rungs became more widespread and prompted patents such as Werner, U.S. Pat. No. 4,656,721 and Thompson et al., U.S. Pat. No. 5,317,798. These described methods of manufacturing D-rung ladders and led to further acceptance of the newer, safer ladders. In the recent past, extruded aluminum ladders were manufactured with C-side rails and round hollow rungs. Such ladders had inherent safety drawbacks, as delineated by Thompson et al. in U.S. Pat. No. 5,317,798. To overcome these safety drawbacks of cylindrical rungs, non-cylindrically shaped rungs developed with the preferred form being the D-shaped rungxe2x80x94known as the D-rung.
In a D-rung ladder, the rungs are set into a D-shaped aperture in the side rail with the flat side of the rung positioned at an angle, typically 15xc2x0 (approx.), to the horizontal plane of the ladder when the ladder is vertically disposed. Then, as described above, with the ladder set at the optimal operative angle, against a vertical surface, the D-rung angle is complementary thereto and the flat or step side of the D-rung is substantially horizontal and parallel to the ground. In addition, the D-rung provides more safety as rotation within the mounting hole in the side rail is precluded. The popularity of the D-rung ladder has grown as the configuration provides more comfort to a person standing on the rung for an extended period of time than did the older style round-rung ladders.
In preparing for this disclosure, several patents became known to the inventor hereof and include the following:
Wilsonxe2x80x94U.S. Pat. No. 6,474,607xe2x80x94issued Nov. 5, 2002
Wilson describes paint container support device which includes a hook to suspend the paint can from a rung and an elongate holding arm for insertion into a hollow rung to suspend the paint can therefrom. The holding arm has a configuration consistent with the D-rungs of a modern extension ladder.
Jonesxe2x80x94U.S. Pat. No. 6,352,135xe2x80x94issued Mar. 5, 2002
Jones discloses an accessory device for installation on a ladder having hollow rungs. The device includes a holding arm shaped to be inserted within the ladder rung and the arm has a flat top to prevent rotation thereof. The holding arm is hollow and mounted within one end thereof is a leveling ratchet assembly for rotating an assembly coupled thereto.
U.S. Pat. No. 5,236,161xe2x80x94Havenxe2x80x94issued Aug. 17, 1993
Haven discloses a paint roller tray releasably attached to a side rail of the ladder by means of a bracket and clamping mechanism, the clamping mechanism being releasably engagable to either side rail and slidable along the slide rail as the painter moves up and down the ladder.
U.S. Pat. No. 5,135,193xe2x80x94Parrisxe2x80x94issued Aug. 4, 1992
Parris discloses a tray assembly for attachment to two adjacent hollow rungs. A primary means of attachment is provided by a shaft passing through the uppermost of the two hollow rungs and on the opposite side from the tray a clip is attached. A secondary connector is an L-shaped support that depends from the shaft and inserts into the lowermost hollow rung.
U.S. Pat. No. 4,702,446xe2x80x94Brownxe2x80x94issued Oct. 27, 1987
Brown discloses a ladder caddy designed to support a paint pail and paint brush. The entire fixture is held to the ladder simply by inserting the tubular holding arm into a rung of the ladder. The device has a metal band that fastens about the paint pail. The device depends from a round tube mounted in a round rung to maintain the paint level in a horizontal plane.
U.S. Pat. No. 4,662,594xe2x80x94Dubisxe2x80x94issued May 5, 1987
Dubis discloses a tray attached to a ladder having hollow, round rungs to provide a tray or work base for use while working on the ladder. The device has an expandable member which is placed within the rung. This expandable member functions like an expansion bolt, in than in an unexpanded condition has a diameter which is slightly smaller than the inner diameter of the rung, and, upon expansion, presses against the interior wall of the rung.
U.S. Pat. No. 4,660,794xe2x80x94Givenxe2x80x94issued Apr. 28, 1987
Given discloses a ladder tray mounted in one hollow rung of the ladder, which tray is adjustable so as to be held to a nearly level position regardless of the angle of the ladder. On the side of the ladder opposite the tray, a stabilizer block engages the rail of the ladder.
U.S. Pat. No. 4,523,733xe2x80x94Lunden. Jr.xe2x80x94issued Jun. 18, 1985
Lunden discloses a paint or stain can holder which is suspended from a rod having an outside diameter of one inch to fit within a round hollow rung.
U.S. Pat. No. 4,445,659xe2x80x94LaChancexe2x80x94May 1, 1984
LaChance discloses a paint tray holder that, in a manner similar to Parris, supra, attaches to two rungs of the ladder. The tray is adjustable so that it can be always level relative to the ground or in any other angular position, regardless of the angle at which the ladder is placed against a structure.
U.S. Pat. No. 4,186,903xe2x80x94Fazakerleyxe2x80x94issued Feb. 5, 1980
Fazakerley discloses a spring insert for a hollow rung with the insert having an upper leaf and a lower leaf, which lower leaf extends beyond the side rail of the ladder and terminates in a lip section for receiving the bail of a paint can and a hook thereabove for a paint brush.
U.S. Pat. No. 4,099,693xe2x80x94Blannxe2x80x94issued Jul. 11, 1978
Blann discloses a hook formed from a xe2x85x9c-inch steel rod for holding a paint can. The hook has a stem extended through a hollow rung from side rail to side rail with a catch at one end and a hanger at the other. The hanger includes a flange to support the side of the paint can.
U.S. Pat. No. 3,822,846xe2x80x94Jesionowskixe2x80x94issued Jul. 9, 1974
Jesionowski discloses a paint tray which in one embodiment is mounted on a ladder by a clamp about the surface of a tread of a wooden ladder and in a second embodiment is mounted by a cam locking member into a hollow rung. The cam locking device has a offset cam rod constructed to bear against the interior wall of the hollow rung.
U.S. Pat. No. 3,223,369xe2x80x94J. A. Benninger. Jr.xe2x80x94issued Dec. 14, 1965
Benninger discloses a paint can hanger having a tubular member with a wire spring lock that fit within the round, hollow rung and a grooved boss that extends beyond the side rail.
These patents are representative of the present state-of-the-art, but do not singly or in combination exhibit the characteristics of the paint tray holder presented, infra. The citing of the above patents is not intended as an admission that any such patent constitutes prior art against the claims of the present application. Applicant does not waive any right to take any action that would be appropriate to antedate or otherwise remove any listed document as a competent reference against the claims of the present application.
Other technical problems are overcome or resolved by the invention disclosed herein. The innovative approach becomes apparent in the description which follows.
The invention disclosed hereby is a tray holding device for mounting to a D-rung ladder. The device has a shaft adapted to be inserted into an outwardly facing D-shaped aperture of the ladder and to slidably engage the inner wall of the hollow D-rung. A tray extends from the shaft and, when installed in the D-rung of a ladder in an operative position, is disposed substantially horizontally. In one embodiment of the invention, a tray holding device has a mounting shaft that is D-shaped in cross-section and configured to telescopically fit within a D-shaped opening of a hollow rung. Optionally, as this is fabricated from reinforced thermoplastic material, the shaft is molded in a slightly bowed condition and, when in use, is under flexural tension.
Alternatively, in another embodiment, molded into the thermoplastic portion of the disclosed device is an extruded metal shaft. Here, any number of cross-sectional configurations may be chosen, which slidably engage the interior wall of the rung cavity. Several of these mounting shafts engage both the flat side and the curved side of the D-rung cavity and enable the tray holding device to be reversibly insertable into one of the D-shaped openings. The cross-sectional configurations shown all preclude rotation within the D-rung while permitting reversibility.
Because of the fabrication techniques employed, tray support structures are described which buttress the underside of the tray and enhance the load carrying capacity of the paint tray holder.
It is an object of this invention to provide a paint tray accessory for installation on a ladder having D-shaped rungs.
It is another object of this invention to provide a paint tray accessory which is economically manufactured by injection molding from a thermoplastic material.
It is yet another object of this invention to provide a paint tray accessory which is readily insertable into a D-rung of a ladder.
It is a feature of this invention that the use of the D-rung cavity prevents unwanted rotation of the paint tray accessory.
It is another feature of this invention that the paint tray holder may be reversible with (or without) a low-raised edge on one side and a high-raised edge on the other.
It is yet another feature of this invention that the shaft inserted into the D-rung, while being under tension, is readily released therefrom for placement at another location.
Other objects and features of this invention will become apparent from the following drawings and Description of the Preferred Embodiments set forth hereinbelow.